Webwork2 tutorial (Chinese version) (5) (End)

5, Interceptors

Interceptors allows code that is executed after the calling stack is included before and / or processing before processing. This is your code simple, more reuse. Most of XWork and WebWork is implemented in Interceptors. You can apply your own interceptors to the specified action by external configuration, according to your defined order. Apply your own Interceptors.

When you visit .Artion URL, WebWork's servletdispatcher boots an action object, starting to be interrupted by other objects before Action is executed, which is called Interceptor. Execute Interceptor before the specified action (or later), as long as the properties are configured in xwork.xml. Here are an Interceptor configuration that shows an example of the UI tag usage in Section 4.1.1:

eX01-index.jsp

eX01-surcess.jsp

FormProcessingAction uses ValidationWorkflowstack. This is an interceptor heap that organizes a set of interceptors in order. ValidationWorkflowStack is configured in WebWork-Default.xml, so we just use in the action configuration, or use to use it in the package configuration. Below is an Interceptor configuration of the HelloWebWorld example:

"http://www.opensymphony.com/xwork/xwork-1.0.dtd">

eX01-surcess.jsp

Look at how Interceptor works

l Create an interceptor class, you need to extend the com.OpenSymphony.xWork.Interceptor.Interceptor interface (included in xwork-1.0.jar);

l In the xwork.xml file, use the embedded embedded in the ;

l Use to create an interceptor heap (optional);

l Which anterceptor is used by or ; the former is used by the specified action, the latter uses all Action

(1) Webwork-default.xml

Let's take a look at the contents of web-default.xml:

"http://www.opensymphony.com/xwork/xwork-1.0.dtd">

Class = "com.opensymphony.webwork.dispatcher.servletdispatcherResult" />

Class = "com.opensymphony.webwork.dispatcher.servletredirectResult" />

Class = "com.opensymphony.webwork.dispatcher.velocityResult" />

Class = "com.opensymphony.xwork.actionchainResult" />

Class = "com.opensymphony.webwork.views.xslt.xsltResult" />

Class = "com.opensymphony.xwork.interceptor.timinterceptor" />

Class = "com.opensymphony.xwork.interceptor.logginginterceptor" />

Class = "com.opensymphony.xwork.interceptor" />

Class = "com.opensymphony.xwork.interceptor.StaticParametersInterceptor" />

Class = "com.opensymphony.xwork.interceptor" />

Class = "com.opensymphony.xwork.interceptor.modeldriveninterceptor" />

Class = "com.opensymphony.xwork.interceptor.component.componentinterceptor" />

Class = "com.opensymphony.webwork.interceptor.tokeninterceptor" />

Class = "com.opensymphony.webwork.interceptor.tokenssionStoreInterceptor" />

Class = "com.opensymphony.xwork.validator.validationinterceptor" />

Class = "com.opensymphony.xwork.interceptor.defaultWorkflowInterceptor" />

Class = "com.opensymphony.webwork.interceptor.servletconfiginterceptor" />

Class = "com.opensymphony.xwork.interceptor.prepareinterceptor" />

Class = "com.opensymphony.webwork.interceptor.webworkconversionerrorinterceptor" />

Since WebWork-Default.xml is included in our xwork.xml, we can use these Interceptor or Interceptor piles in Action. Below is what these Interceptors do:

l Timer: Perform timing (including Nested Interceptor and view)

l Chain: Make the properties of the previous Action valid for the current action, usually create an Action chain

l Static-Params: Setting parameters in xwork.xml to action ( embedded in )

l Params: Settings the request parameter (POST or GET) to the action

l Model-Driven: If the action realizes ModelDriven, push getModel () results into the Value Stack

l Component: Enable and register components to make it valid for Action

l Token: Check the effective token in action to prevent repeated submission

l Token-session: Same as above, but saves submitted data in the session when processed to invalid token

l Validation: Use the validator defined in {Action} -vailDation.xml for data verification

l Workflow: Call the validate () method in the Action class, return to the INPUT view when an error occurs; should be used with the Validation Interceptor

l Servlet-Config: Access to HTTPSERVLETREQUEST and HTTPSERVLETRESPONSE (Because Bind to Servlet API, it is best not to use)

l prepare

l conversionerror

(2) Creating your own interceptor If the above Interceptor is not suitable, you can create your own interceptor. The following example assumes that we need an interceptor to place a welcome information based on the day of the SESSION:

GreetingInterceptor.java:

Package lesson05;

Import java.util.calendar;

Import com.opensymphony.xwork.interceptor.interceptor;

Import com.opensymphony.xwork.actioninvocation;

Public class greetinginterceptor imports interceptor {

Public void init () {}

Public void destroy () {}

Public String Intercept (ActionInvocation Invocation) throws exception {

Calendar Calendar = Calendar.getInstance ();

INT Hour = Calendar.get (Calendar.Hour_Of_DAY);

String Greeting = (Hour <6)? "Good evening":

((Hour <12)? "Good Morning":

((Hour <18)? "good insternoon": "good evening"));

Invocation.getinvocationContext (). GetSession (). PUT ("Greeting", Greeting;

String result = invocation.invoke ();

Return Result;

}

}

Xwork.xml:

"http://www.opensymphony.com/xwork/xwork-1.0.dtd">

eX01-result.vm

GreetingAction.java:

Package lesson05;

Import com.opensymphony.xwork.actionsupport;

Public class greetingaction extends actionSupport {

Public String Execute () throws exception {

RETURN SUCCESS;

}

}

EX01-Result.vm: